Field of the Invention
The present invention relates to the field of direct current breaking devices, and in particular, to a bridge-type circuit and a control method thereof, and a direct current breaking device based on the bridge-type circuit and a control method thereof.
Related Art
With the development of multi-terminal direct current power transmission technologies, a high-voltage direct current breaker will become a key apparatus that ensures a secure and stable operation of a system.
Chinese Patent with publication No. CN102823121A discloses a switch module which is set to limit the current through power transmitting or distribution line and breaking the current in a circuit breaker device, and where an RCD buffer circuit is connected in parallel at each of two ends of a power semiconductor switch device, or every two power semiconductor switch devices that are in series-opposing connection share one full-bridge RCD buffer circuit. Because the direct current breaker needs to break a current of high magnitude, the power semiconductor switch devices are mostly press-connected type devices. The RCD buffer circuit can only be mounted in narrow space defined by the thickness of the heat-dissipation device plus the thickness of the press-connected type power semiconductor switch devices, the sum of the thickness ranging from 50 mm to 80 mm, thus restricting mode selection for diodes and capacitors and their installation. In addition, the direct current breaker uses a large number of power semiconductor switch devices, and therefore there are also a large number of RCD buffer circuits.
Chinese Patent with publication No. CN103280763A discloses a direct current breaker and an implementation method thereof, where a breaking unit and a current conversion unit are formed by connecting full-bridge/half-bridge current converters in cascade. Four power semiconductor switch devices in the full-bridge current converter share one capacitor as a buffer circuit, and two power semiconductor switch devices in the half-bridge current converter share one capacitor as a buffer circuit. This patent uses a small number of buffer circuits and has large installation space as compared with the foregoing patent No. CN102823121A. However, the capacitor of the full-bridge/half-bridge current converter carries a high voltage after the direct current breaker completes a current breaking operation. If a reclosing operation is performed in this case, bridge arms of the full-bridge/half-bridge current converter may short circuit and discharge, resulting in damage to the power semiconductor switch device. Reclosing means that the breaker is switched on in a short period after a circuit failure is cleared. Because most of circuit failures are actually instantaneous or temporary, reclosing is one of power supply self-recovery methods that is frequently used in operation and is an indispensable function of the breaker.
Based on the foregoing problems in the conventional breaker structure, the present invention is produced by in-depth studies of the inventors.